Polar bears have, what seems to us, a long gestation period. A fertilized polar bear egg doesn’t implant or develop right away. Instead, it implants when triggered by the female’s body condition and environmental factors, most often between September and November. This is known as delayed implantation, an adaptation that ensures cubs are born to healthy mothers at a time of year when their chances for survival are greatest. We are in the middle of that time zone right now with our female bear, Chinook. If a fertilized egg were to implant, the actual fetal gestation would be about 60 days.
Keeper Samantha Marino explained that Chinook is starting to be come interested in using bedding materials and desires more “alone time” from Tatqiq and Kalluk on a more regular basis. Keepers are offering Chinook denning/nesting materials, such as Bermuda grass, burlap, and palm fronds, and allowing her to spend the afternoon away from the other bears. They will continue to monitor this behavior and give Chinook what she needs for a possible pregnancy.
Chinook’s urine and feces are collected and sent to our Endocrinology Lab several times a week to determine if there are any changes in her hormone levels that might indicate that hoped-for cubs are on the way. And currently, Chinook is just on exhibit in the morning; in the afternoon and evening, she gets to enjoy the privacy of the off-exhibit polar bear yard, which includes access to the bedroom area.
We will certainly let polar bear fans know if anything changes, but for now it’s just a waiting game. Paws crossed!
Debbie Andreen is an associate editor for San Diego Zoo Global. Read her previous post, Pandas Keep Cool.